lscpu: report more usable cache sizes

The current version reports cache size as reported by /sys, it means
real size of the one piece of the cache. This way provides minimal
overview about all system as the cache is often shared between CPUs.

It seems better to report all size of the caches in the summary
output. It also does not make sense to report sizes per core (or
socket) as CPU topology may be pretty complicated.

The final solution (not implemented yet) will be to have --list-caches
where we can report all details like all-size, item-size, per-core size,
ways, type, etc.

Addresses: https://github.com/karelzak/util-linux/issues/663
Signed-off-by: Karel Zak <kzak@redhat.com>

1 files changed, 41 insertions, 2 deletions

diff --git a/sys-utils/lscpu.c b/sys-utils/lscpu.c
index 1d78dac36..1a03aaf6a 100644
--- a/sys-utils/lscpu.c
+++ b/sys-utils/lscpu.c
@@ -1699,6 +1699,36 @@ print_cpuset(struct libscols_table *tb,
 	}
 }
 
+static int get_cache_full_size(struct lscpu_desc *desc, int idx, uint64_t *res)
+{
+	struct cpu_cache *ca = &desc->caches[idx];
+	size_t setsize = CPU_ALLOC_SIZE(maxcpus);
+	int i, nshares = 0, rc;
+	uint64_t sz;
+
+	/* Convert size to number */
+	rc = parse_size(ca->size, &sz, NULL);
+	if (rc)
+		return rc;
+
+	/* Count number of CPUs which shares the cache */
+	for (i = 0; i < desc->ncpuspos; i++) {
+		int cpu = real_cpu_num(desc, i);
+
+		if (desc->present && !is_cpu_present(desc, cpu))
+			continue;
+		if (CPU_ISSET_S(cpu, setsize, ca->sharedmaps[0]))
+			nshares++;
+	}
+
+	/* Correction for CPU threads */
+	if (desc->nthreads > desc->ncores)
+		nshares /= (desc->nthreads / desc->ncores);
+
+	*res = (desc->ncores / nshares) * sz;
+	return 0;
+}
+
 /*
  * default output
  */
@@ -1872,9 +1902,18 @@ print_summary(struct lscpu_desc *desc, struct lscpu_modifier *mod)
 		add_summary_s(tb, _("Dispatching mode:"), _(disp_modes[desc->dispatching]));
 	if (desc->ncaches) {
 		for (i = desc->ncaches - 1; i >= 0; i--) {
+			uint64_t sz = 0;
+			char *tmp;
+
+			if (get_cache_full_size(desc, i, &sz) != 0)
+				continue;
+			tmp = size_to_human_string(
+					SIZE_SUFFIX_3LETTER | SIZE_SUFFIX_SPACE,
+					sz);
 			snprintf(buf, sizeof(buf),
-					_("%s cache:"), desc->caches[i].name);
-			add_summary_s(tb, buf, desc->caches[i].size);
+					_("%s cache: "), desc->caches[i].name);
+			add_summary_s(tb, buf, tmp);
+			free(tmp);
 		}
 	}
 	if (desc->necaches) {